WASHINGTON - President Bush waded into the debate over evolution and "intelligent design" Monday, saying schools should teach both theories on the creation and complexity of life.

In a wide-ranging question-and-answer session with a small group of reporters, Bush essentially endorsed efforts by Christian conservatives to give intelligent design equal standing with the theory of evolution in the nation's schools.

On other topics, Bush said he has no idea how Supreme Court nominee John G. Roberts would vote in a case challenging the legality of abortion because he never asked him about it. He also defended Baltimore Orioles first baseman Rafael Palmeiro, who was suspended Monday for using performance-enhancing steroids.

Bush declined to state his personal views on "intelligent design," the belief that life forms are so complex that their creation can't be explained by Darwinian evolutionary theory alone, but rather points to intentional creation, presumably divine.

The theory of evolution, first articulated by British naturalist Charles Darwin in 1859, is based on the idea that life organisms developed over time through random mutations and factors in nature that favored certain traits that helped species survive.

Scientists concede that evolution doesn't answer every question about the creation of life, but most consider intelligent design an attempt to inject religion into science courses.

Bush compared the current debate to earlier disputes over "creationism," a related view that adheres more closely to biblical explanations. As governor of Texas, Bush said students should be exposed to both creationism and evolution.

On Monday the president said he favors the same approach for intelligent design "so people can understand what the debate is about."

The Kansas Board of Education is considering changes to encourage the teaching of intelligent design in Kansas schools, and Christian conservatives are pushing for similar changes in other school districts across the country.

"I think that part of education is to expose people to different schools of thought," Bush said. " You're asking me whether or not people ought to be exposed to different ideas, the answer is yes."

The National Academy of Sciences and the American Association for the Advancement of Science have both concluded that there's no scientific basis for intelligent design and oppose its inclusion in school science classes.

"The claim that equity demands balanced treatment of evolutionary theory and special creation in science classrooms reflects a misunderstanding of what science is and how it is conducted," the academy said in a 1999 assessment. "Creationism, intelligent design, and other claims of supernatural intervention in the origin of life or of species are not science because they are not testable by the methods of science."

Some scientists have declined to join the debate, fearing that amplifying the discussion only gives intelligent design more legitimacy.

But advocates of intelligent design also claim support from scientists. The Discovery Institute, a conservative think tank in Seattle that's the leading proponent for intelligent design, said it has compiled a list of more than 400 scientists, including 70 biologists, who are skeptical about evolution.

"The fact is that a significant number of scientists are extremely skeptical that Darwinian evolution can explain the origins of life," John West, associate director of the organization's Center for Science and Culture, said in a prepared statement.

Bush didn't seem eager to talk about the topic.

He was more than ready for questions about his Supreme Court nominee. Bush said he deliberately avoided discussing Roe v. Wade, the 1973 ruling that legalized abortion nationwide, with Roberts before selecting him for a spot on the nation's highest court.

The president said he was concerned that if Roberts expressed an opinion, he would have to withdraw from any case challenging the landmark decision.

"I said there is no litmus test, and I meant it," Bush said.

He also offered an unequivocal defense of Palmeiro, a friend from their days together with the Texas Rangers in the early 1990s. Bush was the team's managing partner when Palmeiro played in Texas.

The Orioles slugger was suspended for 10 days after testing positive for steroid use, despite his insistence that he never intentionally used the prohibited substance. Bush has been an outspoken critic of steroid abuse.

"Rafael Palmeiro is a friend. He testified in public and I believe him," Bush said, referring to Palmeiro's denials under oath to a congressional committee on March 17. "He's the kind of person that's going to stand up in front of the klieg lights and say he didn't use steroids, and I believe him. Still do."

Bush, who leaves Tuesday for a monthlong stay at his Texas ranch, took questions from five Texas reporters at a conference table in the Roosevelt Room, just off the Oval Office. Looking relaxed and upbeat, he sipped on cola and chewed ice as he answered, deflected or bantered his way through questions on a host of topics.

He became most animated when pressed to say whether he personally would like to see Roe v. Wade overturned. Bush opposes abortion, except in cases of rape, incest or to save the mother's life, but he acknowledges that most Americans don't share his views.

"I'm not going to be involved with the Roe v. Wade case in the midst of a judicial nomination," Bush said. "John Roberts is going to be put on the Supreme Court, hopefully, in an expeditious manner, and he will answer the questions put to him. It is clear that if he were to answer those questions, he would have to recuse himself from future cases."

Bush also declined to say much about the investigation into the leak of a CIA officer's identity. A federal grand jury is trying to determine whether presidential aide Karl Rove or anyone else in the White House deliberately exposed Valerie Plame's identity to retaliate against her husband, former Ambassador Joseph Wilson, an outspoken Bush critic.

"Karl's got my complete confidence. He's a valuable member of my team," Bush said. "Why don't you wait and see what the true facts are?"